The objective of this proposal is to advance a delta agonist opioid compound, DP13338W95, into clinical trials as a postoperative treatment for respiratory depression induced by mu-opioid analgesics. It has been shown that DP13338W95 is capable of attenuating respiratory depression produced by mu agonists; it is important to establish whether it can also antagonize other mu- specific effects such as dependence, drug seeking behavior, and emesis. The three aims of this Phase 1 application are to synthesize approximately 2 grams of the compound for further studies, to assess whether DP13338W95 has abuse potential, and to determine which of three clinically used analgesics can best be combined with DE13338W95 to produce adequate analgesia with minimal respiratory depression.